Thin films are routinely used to cover or repair valuable articles. In many applications, these thin films need to be secured in place via an attachment means. Unfortunately, the increased stresses that occur at the interface between the thin film itself and the attachment means often results in premature failure under load. There are many instances where a failure occurs at the interface between the attachment means and the thin film, such as when the surgical polymer film mesh affixed to body tissue during a hernia repair, or a when panels of a filter bag are sewn together, or when a synthetic graft is used in a medical procedure.
U.S. Pat. No. 5,527,341 describes a method of using additional flat membrane layers to reinforce the hole region during tendon augmentation or repair. U.S. Pat. No. 5,797,932 discusses a membrane hernia repair using a “platform-elevated part” approximately equivalent to the thickness of the base membrane. This double membrane thickness is intended to reduce tearing by the suture when after the membrane is stitched in place during the surgery.
U.S. Pat. No. 6,544,167 discusses securing a sheet material such as Dacron (Hemoshield), or polytetrafluroethylene (Gortex) to body tissue by providing a reinforcing “ring which will typically have a toroidal configuration with a circumferential cross section that is circular, and is typically formed of a plastic material or curled autogenous tissue such as fascia or pericardium, or any other biocompatible material.”
US 2002/0026092 A1 discusses a reinforcing “ring can be attached to the material by adhesive or by stitches passing over the ring and through the material. Alternatively, the ring can be sandwiched between two pieces of the sheet material. In this case, a second piece of the sheet material can be positioned on the side of the ring opposite to the sheet material. Appropriate sutures extending around the ring and through the materials and will sandwich the ring and maintain it in the preferred position.
European Patent Application EP0352972A discusses the need for a thin wall expanded polytetrafluoroethylene (PTFE) “vascular graft which resists tearing by the sutures attaching it to perigraft material. [That inventive] composition comprises an expanded biocompatible fluoroplastic resin and biocompatible, high temperature-resistant fibers which are chemically compatible with the PTFE resin, wherein the fibers are distributed throughout the resin in a random orientation.”
The present invention provides a method of increasing tear strength of polymer films as described herein.